# std::bit_not

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< cpp‎ | utility‎ | functional

Defined in header `<functional>` |  |
template< class T = void > struct bit_not; |  | (since C++14)

Function object for performing bitwise NOT. Effectively calls operator~ on type `T`.

### Specializations

The standard library provides a specialization of `std::bit_not` when `T` is not specified, which leaves the parameter types and return type to be deduced.

bit_not<void> (C++14) | function object implementing ~x deducing parameter and return types (class template specialization)

### Member types

Type | Definition
`result_type` (deprecated in C++17)(removed in C++20) | `T`
`argument_type` (deprecated in C++17)(removed in C++20) | `T`

### Member functions

operator() (C++14) | returns the result of bitwise NOT of its argument (public member function)

## std::bit_not::operator()

constexpr T operator()( const T& arg ) const; |  | (since C++14)

Returns the result of bitwise NOT of arg.

### Parameters

arg | - | value to compute bitwise NOT of

### Return value

The result of ~arg.

### Exceptions

May throw implementation-defined exceptions.

### Possible implementation

    constexpr T operator()(const T& arg) const
    {
        return ~arg;
    }

### Notes

Although `std::bit_not` is added via post-C++11 proposal N3421, it is treated as a part of the resolution for LWG issue 660 (except for its transparent specialization `std::bit_not<>`) by common implementations, and thus available in their C++98/03 mode.

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